Continuing from this thread
It's alive and well!
It's 3am, more info after sleep.
Here is a view of the SD card configured for P16-P19 operation.
The changes to the original design:
- Added USB activity LED
- Surface mount power switch
- Reverse polarity protection diode
- Removable pull-up resistor pack for uSD card
- uSD card can be connected to P0-P3 or P16-P19 using solder bridge pads on the back
- Seiko RTC chip with rechargeable supercap battery backup
- External reset connection inserted in top header between P31 and GND
- J11 for access to RTC chip interrupt outputs
- Right angle reset button for easier access
Most up-to-date layout attached, along with a pallpark cost breakdown in ods format. ppusb_rtc.zip